From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0BB12C31E4B for ; Fri, 14 Jun 2019 15:38:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4FF32173C for ; Fri, 14 Jun 2019 15:38:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560526725; bh=s+Zwd+ONqT1pksANmhQFeU8cIb2gGorOOp+WywyUETo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=pZxbYXfrHnf9krx/MM9AndcrPigsnwGOEQAX6a1Sgjkjig+KrkjZzpZ+kVA7xTvf0 xl4MVT80weuvbmEPzoef3ZrXMlGLEzf1Lc0KdqsllawC41A/iOLKDlcVha7160mQgD WJ80CaN1TM3Pw6vG6hPwTcLqbTtJzWvltd3haVcU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726755AbfFNPio (ORCPT ); Fri, 14 Jun 2019 11:38:44 -0400 Received: from mail-pl1-f178.google.com ([209.85.214.178]:44859 "EHLO mail-pl1-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725780AbfFNPin (ORCPT ); Fri, 14 Jun 2019 11:38:43 -0400 Received: by mail-pl1-f178.google.com with SMTP id t7so1167139plr.11 for ; Fri, 14 Jun 2019 08:38:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=KRgtgULPK891tOGG5t4dUW4/Zs8Jf3twwJrLAvaHXCM=; b=o3Lri5DsGsWuggMDg29Bi3ENUTlvH+3GmvfvzTZGh2sF3pkpez5DNm8bBAnAUaEWZZ 3c1JTmWV/+H4DwAEWKuf8SIhFlrkKgyxGA08WQUxcLuuBDucCsPpX5ou261vea4IAUD4 WQYvESfcDZvmL6S+6IRwxsPQuEsCTmLfTKe3hQlII+Ia2XdlgWmUu3rLDCHGq83/HVlt NK28IS/TYC5hON8cjCk4En/YfFspE72vU+HJ/iEGlOPHFGTMVicpAIpXo9xI/uzf5A0u 364X1XL7JKHiGgzJ2Q9GwBwCLBz0Bd91qQovHCccul8GepD3nt7DLEeGJOYTE9baEEe6 mZyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=KRgtgULPK891tOGG5t4dUW4/Zs8Jf3twwJrLAvaHXCM=; b=O4W0D3GqNkEl1OFZs+XHpQS6yIj8voVI1k4UapHWIh3EIO4zZSeou1ftqtcsT/LzmO b3GdRuE8X7vwSrHQrpvEgoTz5p4C7+21cFYrfFaVzkVXIZcryNqaMen4W6F5FCOygzE0 lN2309TLvvDLeEfcpLii58s6FBIAVt5PzaOaEMjyhm5ZtHV8i5XzrUw7zeW/K0toKQLH UZPCujTj863ZzgXEWU6he4C/ht2sH5qJlUDB+OETThrsyQXP93lgulnolUyUK+X/3Lcw YBR3yHY7lpY/QC7XcLYHUjirZDHX+Stt9KrbL3t6TzSqvpRHfacO3tr39NwwJIVn4Tky Y73Q== X-Gm-Message-State: APjAAAUuhY7UvSGHTCc9mh3Yth6RZg0y3b3NQaRot9K17/3LTyy0xBN+ BqC9txORpeG/pYx9N2bUtc8= X-Google-Smtp-Source: APXvYqwiq+8hGeYQ6L6Er98x3qaWhr3zME6PrQeoyZkRUO5Spda7XFFJhNph3wuEpCh6CNK8gyW1Eg== X-Received: by 2002:a17:902:b705:: with SMTP id d5mr57674507pls.274.1560526722616; Fri, 14 Jun 2019 08:38:42 -0700 (PDT) Received: from localhost ([2620:10d:c090:180::1:b330]) by smtp.gmail.com with ESMTPSA id w36sm7563630pgl.62.2019.06.14.08.38.41 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Jun 2019 08:38:41 -0700 (PDT) Date: Fri, 14 Jun 2019 08:38:37 -0700 From: Tejun Heo To: Chris Wilson Cc: Greg Kroah-Hartman , Peter Zijlstra , Steven Rostedt , LKML , Tvrtko Ursulin , David Airlie , Daniel Vetter , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: Re: [BUG] lockdep splat with kernfs lockdep annotations and slab mutex from drm patch?? Message-ID: <20190614153837.GE538958@devbig004.ftw2.facebook.com> References: <20190614093914.58f41d8f@gandalf.local.home> <156052491337.7796.17642747687124632554@skylake-alporthouse-com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <156052491337.7796.17642747687124632554@skylake-alporthouse-com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Fri, Jun 14, 2019 at 04:08:33PM +0100, Chris Wilson wrote: > #ifdef CONFIG_MEMCG > if (slab_state >= FULL && err >= 0 && is_root_cache(s)) { > struct kmem_cache *c; > > mutex_lock(&slab_mutex); > > so it happens to hit the error + FULL case with the additional slabcaches? > > Anyway, according to lockdep, it is dangerous to use the slab_mutex inside > slab_attr_store(). Didn't really look into the code but it looks like slab_mutex is held while trying to remove sysfs files. sysfs file removal flushes on-going accesses, so if a file operation then tries to grab a mutex which is held during removal, it leads to a deadlock. Thanks. -- tejun